Inertial guidance requires gyroscopes and accelerometers to measure the heading and linear motion of a vehicle. Spinning wheel gyroscopes have fallen out of favor in the last two decades relative to novel non-moving parts approaches represented by optical gyroscopes. With the recent development of MEMS (MicroElectroMechanical Systems) technologies, mechanical gyroscopes are again under consideration. The primary driver is that optical devices (Ring Laser Gyroscopes and Fiber-Optic Gyros) are large and do not lend themselves to automated fabrication. The result is that the manufacture of optical gyroscopes requires a large infrastructure and costs are high. The attraction of the MEMS-based microgyros is that they are small, can be integrated with the supporting electronics and can be batch-fabricated for low cost. The result is a great reduction in size, cost and power consumption. However, MEMS gyroscopes are microscopic in size which limits their performance. In addition, they are based primarily on oscillatory motions (Coriolis Effect) for generating angular momentum and for detecting rotational motion.
The Millimachined Flat-Pack Gyroscopes described here combine traditional spinning wheel concepts, that are well-understood, with MEMS technologies extended to larger dimensions to obtain higher performance capability yet retain the cost advantages of batch-processability. The approach is to reduce the conventional three dimensional single-degree-of-freedom design to a planar configuration which can be reduced to a multiple layer set. Each layer is batch-fabricated and the complete gyro is formed by stacking the layers. The electronics can be integrated into each layer as required or can be part of separate layers.
Millimachining is the design and fabrication of instruments and devices based on multi-layers. The functionality of the device is reduced to components which are made up of subcomponents. The subcomponents are located within a layer and the assembly of the layers forms the components and therefore the device. Millimachined devices are assembled by the pure stacking of the layers. The gyro has been converted from a three dimensional entity to a planar configuration which could be reduced to a set of layers. The layers are then fabricatable by modern planar technologies which are batch processable much like the Integrated Circuits.